Differences between @+id , @id and @android:id

Question

Differences between?

• @+id/mywidget
• @id/mywidget
• @android:id/mywidget

Answer 1

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1. you are declaring a new id inside class R(from your app)
2. you are referencing and id inside class R (from your app)
3. you are referencing and id inside class R (from the android.R)

Answer 2

@+id/mywidget

Adds the id to R.java

@id/mywidget

References an existing id

@android:id/mywidget

References an id that exists in android.R.java, e.g. resources that are already provided by the framework

Answer 3

1. @+id/mywidget - you are defining new id mywidget
2. @id/mywidget - you are referencing already defined id mywidget
3. you are referencing an id mywidget from Android